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<!--
https://bugzilla.mozilla.org/show_bug.cgi?id=634373
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<head>
  <title>Test for Bug 634373</title>
  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
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<body>
<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=634373">Mozilla Bug 634373</a>
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<div id="content" style="display: none">
  
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<pre id="test">
<script type="application/javascript">

/** Test for Bug 634373 **/

function make_rule_and_remove_sheet(text, getter) {
  var style = document.createElement("style");
  style.setAttribute("type", "text/css");
  style.appendChild(document.createTextNode(text));
  document.head.appendChild(style);
  var result = style.sheet.cssRules[0];
  if (getter) {
    result = getter(result);
  }
  document.head.removeChild(style);
  style = null;
  SpecialPowers.DOMWindowUtils.garbageCollect();
  return result;
}

var gDisplayCS = getComputedStyle(document.getElementById("display"), "");

function keep_rule_alive_by_matching(rule) {
  // It's the caller's job to guarantee that the rule matches a p.
  // This just causes a style flush, which in turn keeps the rule alive
  // until the next style flush.
  var color = gDisplayCS.color;
  return rule;
}

function get_rule_and_child(rule) {
  return [rule, rule.cssRules[0]];
}

function get_only_child(rule) {
  return rule.cssRules[0];
}

var rule;

// In this case, the rule goes away immediately, so we're testing
// the DOM wrapper's handling of a null rule, rather than the rule's
// handling of a null sheet.
rule = make_rule_and_remove_sheet("p { color: blue }");
rule.style.color = "";
try {
  rule.style.color = "fuchsia";
} catch(ex) {}

rule = make_rule_and_remove_sheet("p { color: blue }",
                                  keep_rule_alive_by_matching);
try {
  rule.style.color = "";
} catch(ex) {}
try {
  rule.style.color = "fuchsia";
} catch(ex) {}

rule = make_rule_and_remove_sheet("@media screen { p { color: blue } }",
                                   get_rule_and_child);
rule[1].style.color = "";
try {
  rule[1].style.color = "fuchsia";
} catch(ex) {}

// In this case, the rule goes away immediately, so we're testing
// the DOM wrapper's handling of a null rule, rather than the rule's
// handling of a null sheet.
rule = make_rule_and_remove_sheet("@media screen { p { color: blue } }",
                                   get_only_child);
rule.style.color = "";
try {
  rule.style.color = "fuchsia";
} catch(ex) {}

rule = make_rule_and_remove_sheet("@media screen { p { color: blue } }",
                                  function(rule) {
                                    return keep_rule_alive_by_matching(
                                             get_only_child(rule));
                                  });
try {
  rule.style.color = "";
} catch(ex) {}
try {
  rule.style.color = "fuchsia";
} catch(ex) {}

rule = make_rule_and_remove_sheet("@keyframes a { from { color: blue } }");
rule.appendRule("from { color: fuchsia}");
rule.deleteRule("from");
rule.name = "b";
rule.cssRules[0].keyText = "50%";

ok(true, "didn't crash");

</script>
</pre>
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